# File: backend/app/models/pydantic_models.py (Update Read models, add Message models)
# Description: Pydantic 模型定义 API 数据结构

from pydantic import BaseModel, Field
from typing import Optional, List
import uuid
from datetime import datetime # Use datetime directly

# --- Assistant Models ---

class AssistantBase(BaseModel):
    """助手的基础模型，包含通用字段"""
    name: str = Field(..., min_length=1, max_length=50, description="助手名称")
    description: Optional[str] = Field(None, max_length=200, description="助手描述")
    avatar: Optional[str] = Field(None, max_length=5, description="头像 Emoji 或字符")
    system_prompt: str = Field(..., min_length=1, max_length=4000, description="系统提示")
    model: str = Field(..., description="使用的 LLM 模型")
    temperature: float = Field(0.7, ge=0.0, le=1.0, description="温度参数 (0.0-1.0)")
    # 可以添加 top_p, max_tokens 等

class AssistantCreate(AssistantBase):
    """创建助手时使用的模型 (不需要 ID)"""
    pass

class AssistantUpdate(BaseModel):
    """更新助手时使用的模型 (所有字段可选)"""
    name: Optional[str] = Field(None, min_length=1, max_length=50)
    description: Optional[str] = Field(None, max_length=200)
    avatar: Optional[str] = Field(None, max_length=5)
    system_prompt: Optional[str] = Field(None, min_length=1, max_length=4000)
    model: Optional[str] = None
    temperature: Optional[float] = Field(None, ge=0.0, le=1.0)

class AssistantRead(AssistantBase):
    """读取助手信息时返回的模型 (包含 ID)"""
    id: str = Field(..., description="助手唯一 ID")
    created_at: datetime # Add timestamps
    updated_at: Optional[datetime] = None
    class Config:
        from_attributes = True # Pydantic v2: orm_mode = True

# --- Chat Models (更新) ---

class ChatRequest(BaseModel):
    """聊天请求模型 (添加 sessionId 和 assistantId)"""
    message: str
    session_id: str = Field(..., description="当前会话 ID (可以是 'temp-new-chat')")
    assistant_id: str = Field(..., description="当前使用的助手 ID")

class ChatResponse(BaseModel):
    """聊天响应模型"""
    reply: str
    session_id: Optional[str] = None # (可选) 如果创建了新会话，返回新 ID
    session_title: Optional[str] = None # (可选) 如果创建了新会话，返回新标题

# --- Session Models ---

class SessionCreateRequest(BaseModel):
    """创建会话请求模型"""
    assistant_id: str
    first_message: str # 用户的第一条消息，用于生成标题

class SessionCreateResponse(BaseModel):
    """创建会话响应模型"""
    id: str
    title: str
    assistant_id: str
    created_at: str # 返回 ISO 格式时间字符串

class SessionRead(BaseModel):
    """读取会话信息模型"""
    id: str
    title: str
    assistant_id: str
    created_at: datetime # Use datetime
    updated_at: Optional[datetime] = None

    class Config:
        from_attributes = True

# --- Message Models (New) ---
class MessageBase(BaseModel):
    sender: str # 'user' or 'ai'
    text: str

class MessageRead(MessageBase):
    id: str
    session_id: str
    order: int
    created_at: datetime

    class Config:
        from_attributes = True